EXAMINATION OF A GREAT ABUNDANCE OF FILEFISH, PERVAGOR SPILOSOMA, IN HAWAII

The endemic filefish Pervagor spilosoma appeared in exceptionally larg e numbers throughout the major Hawaiian Islands during the spring of 1 985 and remained abundant through 1988. We examined this occurrence wi th a perspective gained from studies of reef communities at the Island of Hawaii by one or both of us during most years from 1969 to 1994. P . spilosoma is known to vary in numbers, but such great abundances are rare. Although the species is considered a reef fish, individuals con stituting the abundance were mostly in the water column, and spread fr om coastal reefs to the pelagic zone offshore. One might assume they r epresented an extraordinary recruitment of pelagic juveniles in the pr ocess of shifting to benthic habits, but our data indicate a more comp lex situation. Individuals in the water column tended to be larger tha n individuals near the reef, and although the former were feeding on p lankton when collected, many had shifted to planktivory from earlier f eeding on the benthos. Also, many in the water column were ailing, wit h moribund and dead individuals common, and these tended to carry para sites of types known to induce their hosts to rise toward the surface. We suggest that the great number of filefish we observed above near-s hore reefs represented the shoreward fringe of a vast pool of individu als, varied in age, that had accumulated during the exceptionally long pelagic-juvenile period that is characteristic of tetraodontiforms.